Process for cracking oil



April 7, 1931- R. T. POLLOCK v 1,799,530

PROCESS FOR CRACKING OIL Original Filed Nov. 24, 1920 Far lace PatentedApr. 7, 1931 ROBERT T. POLLIOOK, OF NEW YORK, N. Y.,

PATENT OFFICE ASSIGNOR TO UNIVERSAL OIL PRODUCTS COMPANY, OF CHICAGO,ILLINOIS, A CORPORATION OF SOUTH DAKOTA lPROCESS FOR CRACKING OILApplication filed November 24, 1920, Serial No. 426,313. Renewed March24, 1927.

This invention relates to improvements in a process for cracking oil andrefers more particularly to a continuous process in which the raw oiland reflux condensate are introduced as charging stock into the heatingzone.

The object of the invention is to provide a process and apparatus inwhich the charging stock consists of regulated proportions of refluxcondensate and raw oil, the proportion being regulated through anorifice valve. In this process, the charging stock is at all times keptout of contact with the carbon in the expansion or vapor chamber. Thetemerature of the dephlegmator is regulated y water or other fluid whilethe raw oil is preheated and acts as the cooling medium in the finalcondenser. The reason for this is that more raw oil is required tocontrol the temperature of the dephlegmator than is used in the system.Less cooling medium is required in the final condenser and moreover, thevapors which reach the final condenser are at a lower temperature thanin the dephlegmator.

As a feature of the invention the oil is subjected todiflerentialpressures in various parts of the system. The refluxcondensate and raw oil are thereby positively delivered 80 by pumppressure to the heating coil.

In the drawing, the single figure shows a view, partly in side elevationand partly in vertical section, of my improved apparatus; the view beingsomewhat diagrammatic.

Referring in detail to the drawing, 1 des- "ignates the furnace,provided with the stack- 2, and burner 3. In this furnace is mounted theheating coil 4, which in the present instance takes the form of a closedcoil, as for example, 4" pipe, although the form of this heating coilmay be varied. The outlet side of the coil 4 is connected by transferline 5 having reducing valve 6 to the upper portion of an expansion orvapor chamber 7 This expansion or vapor chamber 7 may take the form of alarge vertical drum or cylinder. It is provided with a liquid residuedrawoflt' pipe 8 controlled by throttle valve 9; both the coil andexpansion chamber are equipped with pressure gauges 10 and 11. Theexpansion chamber is provided with the vapor outlet pipe 12 controlledby throttle valve 13 and leading to the lower end of dephlegmator 14,which dephlegmator is provided with a spiral baflle member 15. Thisdephlegmator 14 is provided with a trap 16, the bottom of which isconnected to the reflux condensate pipe 17 having throttle valve 18leading back to the main feed line 19. The lower end of the pipe 17 isconnected to the pipe 19 through a manually adjustable orifice valve 20,the arrangement being such that the orifice can be adjusted so as tofeed only a regulated quantity of reflux condensate to the feed line 19.The pipe 17 is of sufficient capacity to take care of any excess refluxcondensate. The upper part of the dephlegmator is provided with a vaporoutlet pipe 21 having throttle valve 22 connected to the upper part ofthe final condenser 23.

Referring back to the dephlegmator 14, the oil chamber is formed by thepartitions 24 and 25 forming the upper and lower water chambers 26 and27 connected to each other by a series of water tubes or ipes 28. Wateris fed through-these pipes y means of the pump 29,.delivery line 30,return line 31,

Water cooler 32 and line 33 leading to the M inlet side of the pump. Awater leg 34 may also be provided as shown. The water circu latingsystem is provided with the throttlevalves 35, 36, 37 and 38. Thearrangement is such that the temperature of the dephlegmator may bemaintained at any desired temperature by the water circulating system,thus insuring of close control of the reflux condensate and making thedephlegmator independent of' changes in weather conditions,

due to drops or rises in temperature, rain 01" change in wind velocity,all of which afiect dephlegmation and thus the entire system.

Continuing the description of the appae ratus, thus final condenser 23is provided with the partition members 39 and 40, forming the uppervapor chamber 41 and oil chamber 42 connected by means of the series oftubes 43. The lower chamber 42 is connected by pipe 44 having throttlevalve 45 to receiver 46. This receiver 46 'has pressure gauge 47, liquidlevel gauge 48, drawofi pipe 49 having throttle valve 50 and as outletpipe 51 having throttle valve 52. pressure gauge 53 is provided for thedephlegmator and a pressure gauge 54 for the vapor chamber of thecondenser. In the compartment formed between the two partition membersof the condenser is mounted a spirally formed bafiie 55. Raw oil isintroduced into this chamber through the feed line 56 having a throttlevalve 57 by any suitable pump, not

shown, and is caused to pass down the baflies and the preheated oil isdrawn ofi through the line 58 having throttle valve 59 connected to themain feed line 19. A pump 60 may be interposed in the line 17 ifdesired.

In view of the fact that the system is operated under difierentpressures, a pump 61 is interposed in the feed line so as to be able toforce the charging stock composed of the reflux condensate and raw oilinto the heating coil.

The process is operated as follows: Raw oil, as for example, fuel oil orheavy Mexican or California crudes is continuously fed through the rawoil line and thence through the condenser where after the system isoperating, it is preheated. From the lower part of the condenser, theraw oil passes into the main feed line where it meets and is mixed withthe reflux condensate. The raw oil, preferably in liquid phase andheated to a temperature of say, 650 degs. to 750 degs. F. is deliveredto the expansion chamber, where vaporization takes place. The residuecontaining the precipitated carbon is drawn oflI' continuously out ofthe system. The vapors pass through the dephlegmator which -ismaintained through the water circulating system at any predeterminedtemperature, say 420 dogs. F.; all the vapors which will condense a ovethis temperature are drawn ofi as reflux condensate and fed back throughthe system. Vapors having a lower boiling point than this pass to thefinal condenser where'they are collected in the receiver. The raw oilgoing in serves to condense the final vapors and the vapors also act asa preheater for the raw oil.

It is to be particularly noted that by regulating the orifice valve inthe reflux condensate return line, regulated quantities of refluxrelative to the amount of raw oil can at all times be fed throu h thesystem. For

example, the orifice may e so regulated that the percentage of refluxwill be for example, say, four parts of reflux to one part of raw oil;this rcentage, of course, can be varied both with the character of theoil and the end point product desired. By means of the present process,from 35% to 40% of the entire raw oil may be converted into .420 degs.end point gasoline, which end point, of course, may be varied ifdesired.

The entire system may be operated under a differential pressure, whichmay be accomand the dephlegmator and condenser and receiver atatmospheric pressure or at a reduced pressure of say, pounds.

I claim as my invention:

1. A process for cracking oils, consisting in passing the oil through aheating zone and thence to an expansion chamber, taking the vaporsfromthe expansion chamber and sub-' jecting them to a refluxcondensation in a dephlegmator, in cooling the vapors in thedephlegmator by a regulatable supply of cool liquid, in leading vaporsfrom the ephlegmator to a condenser, in supplying raw oil to thecondenser to condense the vapors and preheat the raw oil, and in mixingthe preheated raw oil with the reflux condensate from the dephlegmatorand leading the mixture free from unvaporized residue under pumppressure to the heating zone, main-. taining a pressure substantiallyabove atmospheric on the heating zone and substantially less pressure onthe expansion chamber, dephlegmator and condenser.

2. A process for cracking oils consisting in passing the oil through aheating zone, and thence to an expansion chamber, taking off the vaporsfrom the expansion chamber preheated raw oil with {apredeterminedquantity of reflux condensate, and in forc ng the mixedoils free from unvaporized residue under pressure through the heatingzone,

maintaining a pressure substantially above atmospheric on the heatingzone and materially reducing said pressure so as to maintain theexpansion chamber, dephlegmator and condenser under a less pressure.

3. A process for cracking oils comprising passing the oil through aheating zone and thence to an expansion chamber, taking vapors from theexpansion chamber and subjecting them to reflux condensation in adephlegmator, cooling the vapors in said dephlegmator by a regulatablesupply of cool liquid, leading vapors from the dephlegmator to thecondenser, supplying raw oil to the condenser to condense the vapors andpreheat the raw oil,- mixing the perheated raw oil with the refluxcondensate from the dephlegmator, supplying the mixture under a pumppressure directly to the heating zone without prior admission to saidexpansion chamber and maintaining a regulated pressure above atmosphericon the oil undergoing treatment in the rocess.

ROB RT T. POLLOCK.

